The invention relates generally to an apparatus for manufacturing a length of sheet metal by continuous casting, and more particularly to such apparatus having a pair of chill rolls to be driven in opposite directions, between which a molten metal is continuously supplied to directly form a length of sheet metal which may be subjected to rolling treatment as occasion demands.
The molten metal to be formed into a continuous sheet according to the invention may be any steel, steel alloy, stainless steel, various non-ferrous metals such as copper, aluminum and various alloys thereof.
The thickness of the sheet metal formed according to the invention is not critical but practically thinner than 10 mm, and preferably of a few or several millimeters. Of course it is possible to form the sheet metal even thinner.
The sheet metal may be and has actually been manufactured by feeding a molded formed ingot, billet or the like between a pair of driven rolls in a hot or cold working method, while suitably adjusting the gap therebetween. By repeating this rolling treatment while adjusting the gap to be gradually narrower or feeding between subsequently arranged pairs of rolls whose gaps are set narrower, sheet metal of a desired thickness can be obtained.
According to the continuous casting method, molten metal is poured from a tundish into a cooled mold whose bottom is open so that the formed metal of, e.g., T-shape in the transverse section thereof, is continuously drawn downwards by a pair of or pairs of pinch rolls and then cut in a desired length. When using a thin slit die or nozzle as the mold, the sheet metal can be continuously formed by casting. When using a pair of chill rolls themselves as the mold, the same purpose can be attained.
Such apparatus is disclosed for instance in Japanese Gazette Sho-56(1981)-80362 published on July 1, 1981 based on the Patent Application filed by Kawasaki Steel Corp. in Kobe, Japan on Dec. 6, 1979. Sheet metal is continuously formed by pouring molten metal from a supply nozzle into a gap having a set size between a pair of rolls arranged below the supply nozzle. The rolls are driven to revolve in different directions to each other so that the sheet metal cooled and formed thereby is continuously fed downwards. The apparatus further includes a tapered outlet guide convergent downwards just below the rolls, a nozzle for jetting air or preferably inert gas just below the outlet guide and a nozzle for jetting water just below the gas nozzle so that the still hot sheet metal is further cooled and protected from ambient air and consequently prevented from being oxidized more or less depending on the nature of the metal or alloy, by water spray which may be encouraged by the gas jet.
In the J-A No. 80362/1981, there is disclosed another embodiment, in which the molten metal is poured from the similar supply nozzle on the circumferential surface of a single roll drivingly rotated so that the sheet metal is continuously formed on the rotating roll and further cooled by the similar gas and water jet to be protected from oxidizing.
Putting the effect of preventing oxidation of the still hot sheet metal aside, the arrangement of the supply nozzle and the single roll or the pair of rolls is not satisfactory in that the molten material contained in and fed from the nozzle cannot be held unruffled which causes metallographical uneveness in the formed sheet metal and uneven thickness of the sheet. Above all, in the second embodiment, there may be caused metallographical differences between one side of the sheet metal contacted with the single chill roll and the other side cooled by ambient air.